When contents are transmitted between digital AV apparatus, encryption is executed on a content transmission device side, and information for decryption is shared between the content transmission device side and a content reception device side. Thereby, copy protect preventing creation of copy without restrictions is executed such that the contents are correctly received and not decrypted by a device other than the content reception device which is a transmission destination.
There is a system described in, for example, Patent Literature 1 which is adopted in digital AV apparatus as an example of a method of such copy protect. According to the system described in Patent Literature 1, contents are classified into “Copy free (copiable without restrictions)”, “Copy free with EPN asserted (copiable without restrictions with output protection)”, “Copy one generation (copiable for one generation)”, “No more copies (prohibit recopy)”, and “Copy never (prohibit copy)” to manage the contents. In a picture recording device, only contents of “Copy free”, “Copy free with EPN asserted”, and “Copy one generation” are recorded, contents of “Copy one generation” are treated as “No more copies” after once recorded, and transmission is executed by subjecting the contents to an encryption processing on a transmission side except contents of “Copy free”. Thereby, copying of contents without restrictions is prevented.
Patent Literature 1 and Patent Literature 2 disclose a technology for determining an intra-residential network such that contents configuring a copyright protection object of broadcasting programs recorded in a household are not delivered extra-residentially without restrictions in contents transmission in a wired or wireless network.